Recording of information from gaseous discharge display/memory panel

ABSTRACT

There is disclosed the generating and recording of image information from a multiple gaseous discharge display/memory panel having an electrical memory and capable of producing information in the form of a visual or latent image, the panel being characterized by an ionizable gaseous medium in a gas chamber formed by a pair of opposed dielectric material charge storage members which are respectively backed by an array of conductor (electrode) members, the conductor members behind each dielectric material member being appropriately oriented with respect to the conductor members behind the opposing dielectric material member so as to define a plurality of discrete discharge volumes, each of which constitutes a discharge unit, the visual or latent image being comprised of one or more discharge units, and image radiation from the discharge units being projected onto a photosensitive surface adapted to receive and electrostatically record the image. The projected image radiation may be visible or latent (invisible) relative to the human eye. The panel may also be of a monolithic construction with the dielectric and electrode arrays being on a common substrate.

United States Patent [1 1 Brown [451 July 22,1975

1 RECORDING OF INFORMATION FROM GASEOUS DISCHARGE DISPLAY/MEMORY PANEL Related US. Application Data [63] Continuation-in-part of Ser. No. 101,102, Dec. 23,

1970, Pat. NO. 3,821,748.

[52] US. Cl. 346/74 P; 340/173 PL; 355/3 [51] Int. Cl.. H01j 61/33; GOld 15/06; H05h 41/44 [58] Field of Search 346/74 ES, 74 P, 74 EL, 346/74 EX; 355/3, 5, 10; 307/88 ET; 340/173 PL [56] References Cited UNITED STATES PATENTS 3,199,086 8/1965 Kallmann 346/74 P 3,499,167 3/1970 Baker 340/173 PL 3,517,206 6/1970 Oliver 307/88 ET 3,543,248 11/1970 Oliver... 307/88 ET 3,559,190 l/l971 Bitzer... 340/173 PL 3,723,977 3/1973 Schaufele 340/173 PL Primary ExaminerBernard Konick Assistant Examiner.lay P. Lucas Attorney, Agent, or Firm-Donald Keith Wedding [5 7 ABSTRACT There is disclosed the generating and recording of image information from a multiple gaseous discharge display/memory panel having an electrical memory and capable of producing information in the form of a visual or latent image, the panel being characterized by an ionizable gaseous medium in a gas chamber formed by a pair of opposed dielectric material charge storage members which are respectively backed by an array of conductor (electrode) members, the conductor members behind each dielectric material member being appropriately oriented with respect to the conductor members behind the opposing dielectric material member so as to define a plurality of discrete discharge volumes, each of which constitutes a discharge unit, the visual or latent image being comprised of one or more discharge units, and image radiation from the discharge units being projected onto a photosensitive surface adapted to receive and electrostatically record the image. The projected image radiation may be visible or latent (invisible) relative to the human eye. The panel may also be of a monolithic construction with the dielectricand electrode arrays being on a common substrate.

12 Claims, 5 Drawing Figures RECORDING OF INFORMATION FROM GASEOUS DISCHARGE DISPLAY/MEMORY PANEL RELATED APPLICATION This is a continuation-impart of my copending US. Pat. application Ser. No. 101,102, filed Dec. 23, 1970,

now US. Pat. No. 3,821,748 the filing date of which is hereby claimed under 35 U.S.C. 120.

BACKGROUNDOF THE INVENTION This invention relates to novel multiple gas discharge display/memory panels which have an electrical memory and which are capableof producing a visual image display or a latent image,e.g., arepresentation of data such as numerals, letters, television display, radar displays, binary words, etc. More particularly, this invention relates to the generating and recording of visualor latent information from a gas discharge display/memory panel. 1

Multiple gas discharge display and/or memory panels of one particular typewith which the present invention is concerned are characterized by an ionizable gaseous medium, usually a mixture of at leasttwo gases at an appropriate gas pressure, in a thin gas chamber or space between a pair of opposed dielectric charge storage members which are backed by conductor (electrode) members, the conductor members backing each dielectric member being appropriately oriented so as to define a plurality of discrete gas discharge units or cells. Typically, the conductors in an array are parallel and transversely positioned relative to the parallel conductors in the opposite array. r

In some prior art panels the discharge cells are additionally defined by surrounding or confining physical structure such as apertures in perforated glass plates and the like so as to be physically isolated relative to other cells. In either case, with or without the confining physical structure, charges (electrons, ions) produced upon ionization of the elementalg'as volume of a selected discharge cell, whenv proper alternating operating potentials .are applied to selected conductors thereof, are collected upon the surfaces of the dielectric at specifically defined locations and constitute an electrical field vopposingthe electrical field which created them so as to terminate the discharge for the remainder of the half cycle and aid in the initiation of a discharge on a succeeding opposite half cycleof applied voltage, such charges as are stored constituting an electrical memory.

Thus, the dielectric layers prevent the passage of substantial conductive current from the conductor members to the gaseous medium and also serve as collecting surfaces for ionized gaseous medium charges (electrons, ions) during the alternate half cycles of the AC. operating potentials, such charges collecting first on one elemental or discrete dielectric surface area and then on an opposing elemental or discrete dielectric surface area on alternate half cycles to constitute an electrical memory.

An example of a panel structure containing nonphysically isolated or open discharge cells is disclosed in U.S. Pat. No. 3,499,167 issued to Theodore C. Baker, et al.

An example of a panel containing physically isolated cells is disclosed in the article by D. L. Bitzer and H. G. Slottow. entitled The Plasma Display Panel A Digitally Addressable Display With Inherent Memory, Proceeding of the Fall Joint Computer Conference, IEEE, San Francisco, California, Nov. 1966, pages 541-547. Also reference is made to US. Pat. No.

In the construction of the panel, a continuous volume of ionizable gas is confined between a pair of dielectric surfaces backed by conductor arrays typically forming matrix elements. The two conductor arrays may be orthogonally related sets of parallel lines (but any other configuration of conductor arrays may be used). The two arrays define at their intersections a plurality of opposed pairs of charge storage areas on the surfaces of the dielectric bounding or confining the gas. Thus, the number of elemental or discrete areas will be twice the number of elemental discharge cells.

In addition, the panel may comprise a so-called monolithic structure in which the conductor arrays are created on a single substrate and wherein two or more arrays are separated from each other and from the gaseous medium by at least one insulating member. In such a device the gas discharge takes place not between two opposing elemental areas on two different substrates, but between two contiguous or adjacent elemental areas on the same substrate; the gas being confined between the substrate and an outer retaining wall.

It is also feasible to have a gas discharge device wherein some of the conductive or electrode members are in direct contact with the gaseous medium and the remaining electrode members are appropriately insulated from such gas, i.e., at least one insulated electrode.

In addition to the matrix configuration, the conductor arrays may be shaped otherwise. Accordingly, while one preferred conductor arrangement is of the crossed grid type as discussed herein, it is likewise apparent that where a maximal variety of two dimensional display patterns is not necessary, as where specific standardized visual shapes (e.g., numerals, letters, words, etc.) are to be formed and image resolution is not critical, the conductors may be shaped accordingly (e.g., a segmented digit display).

The gas is selected to produce visible light and invisible radiation which may be used to stimulate a phosphor (if visual display is an objective) and a copious supply of charges (ions and electrons) during discharge.

In the prior art, a wide variety of gases and gas mixtures have been utilized as the gaseous medium in a number of different gas discharge devices. Typical of such gases include pure gases and mixtures of C0; C0 halogens; nitrogen; Nl-l oxygen; water vapor; hydrogen; hydrocarbons; boron flouride; acid fumes; TiCl air; H 0 vapors of sodium, mercury, thallium, cadmium, rubidium, and cesium; carbon disulfide; H S; deoxygenated air; phosphorus vapors; C 11 CH naphthalene vapor; anthracene; freon; ethyl alcohol; methylene bromide; .heavy hydrogen; electron attaching gases; sulfur hexafluoride; tritium; radioactive gases; and the so-called rare or inert Group VIII gases.

In an open cell Baker, et al. type panel, the gas pressure and the electric field are sufficient to laterally confine charges generated on discharge within elemental or discrete dielectric areas within the perimeter of such areas, especially in a panel containing non-isolated discharge cells. As described in the Baker et al patent, the

. space between the dielectric surfaces occupied by the gas is such asto permit photons generated on discharge in a selected discrete or elemental volume of gas to pass freely through the gas space and strike surface areas of dielectric remote from the selected discrete volumes, such remote, photon struck dielectric surface areas thereby emitting electrons so as to condition at least one elemental volume other than the elemental volume in which the photons originated.

With respect to the memory function of a given discharge panel, the allowable distance the frequency spacing between the dielectric surfaces depends, inter alia, on thefrequency of the alternating current supply, the distance typically being greater for lower frequencies.

While the prior art does disclose gaseous discharge devices having externally positioned electrodes for initiating a gaseous discharge, sometimes called electrodeless discharge, such prior art devices utilized frequencies and spacing or discharge volumes and operating pressures such that although discharges are initiated in the gaseous medium, such discharges are ineffective or not utilized for charge generation and storage at higher frequencies; although charge storage may be realized at lower frequencies, such charge storage has not been utilized in a display/memory device in the manner of the Bitzer-Slottow or Baker, et al. invention.

The term memory margin is defined herein as where V, is the half-of-peak-to-peak amplitude of the smallest sustaining voltage signal which results in a discharge every half cycle, but at which the cell is not bistable and V is the half amplitude of the minimum applied voltage sufficient to sustain discharges once initiated.

It will be understood thatthe basic electrical phenomenon utilized in this invention is the generation of charges (ions and electrons) alternately storable at pairs of opposed or facing discrete points or areas on a pair of dielectric surfaces backed by conductors connected to a source of operating potential. Such stored charges result in an electrical field opposing the field produced by the applied potential that created them and hence operate to terminate ionization in the elemental gas volume between opposed or facing discrete points or areas of dielectric surface. The term sustain a discharge means producing a sequence of momentary discharges, at least one discharge for each half cycle of applied alternating sustaining voltage, once the elemental gas volume has been fired, to maintain alternate storing of charges at pairs of opposed discrete areas on the dielectric surfaces.

As used herein, a cell is in the on state when a quantity of charge is stored in the cell such that on each half cycle of the sustaining voltage, a gaseous discharge is produced.

In addition to the sustaining voltage, other voltages may be utilized to operate the panel, such as firing, addressing, and writing voltages.

A firing voltage is any voltage, regardless of source, required to discharge a cell. Such voltage may be completely external in origin or may be comprised of internal cell wall voltage in combination with externally originated voltages.

An addressing voltage is a voltage produced on the panel X Y electrode coordinates such that at the selected cell or cells, the total voltage applied across the cell is equal to or greater than the firing voltage whereby the cell is discharged.

A writing voltage is an addressing voltage of sufficient magnitude to make it probable that on subsequent sustaining voltage half cycles, the cell will be in the on state.

In the operation of a multiple gaseous discharge device, of the type described hereinbefore, it is necessary to condition the discrete elemental gas volume of each discharge cell by supplying at least one free electron thereto such that a gaseous discharge can be initiated when the cell is addressed with an appropriate voltage signal. I

The prior art has disclosed and practiced various means for conditioning gaseous discharge cells.

One such means of panel conditioning comprises a so-called electronic process whereby an electronic conditioning signal or pulse is periodically applied to all of the panel discharge cells, as disclosed for example in British Pat. Specification No. 1,161,832, page 8, lines 56 to 76. Reference is also made to US. Pat. No. 3,559,190 and The Device Characteristics of the Plasma Display Element by Johnson, et al., IEEE Transactions On Electron Devices, September, 1971. However, electronic conditioning is self-conditioning and is only effective after a discharge cell has been previously conditioned; that is, electronic conditioning involves periodically discharging a cell and is therefore a way of maintaining the presence of free electrons. Ac cordingly, one cannot wait too long between the periodically applied conditioning pulses since there must be at least one free electron present in order to discharge and condition a cell.

Another conditioning method comprises the use of external radiation, such as flooding part or all of the gaseous medium of the panel with ultraviolet radiation. This external conditioning method has the obvious disadvantage that it is not always convenient or possible to provide external radiation to a panel, especially if the panel is in a remote position. Likewise, an external UV source requires auxiliary equipment. Accordingly, the use of internal conditioning is generally preferred.

One internal conditioning means comprises using internal radiation, such as by the inclusion of a radioactive material.

Another means of internal conditioning, which is generally called photon conditioning, comprises using one or more so-called pilot discharge cells in the on state for the generation of photons. This is particularly effective in a so-called open cell construction (as described in the Baker, et al. patent) wherein the space between the dielectric surfaces occupied by the gas is such as to permit photons generated on discharge in a selected discrete or elemental volume of gas (discharge cell) to pass freely through the panel gas space so as to condition other and more remote elemental volumes of other discharge units. In addition to or in lieu of the pilot cells, one may use other sources of photons internal to the panel.

Internal photon conditioning may be unreliable when a given discharge unit to be addressed is remote in dis tance relative to the conditioning source, e.g., the pilot geometric area. In one highly convenient arrangement,

the panel matrix border (perimeter) is comprised of a plurality of such pilot cells.

THE INVENTION In accordance with this invention, a latent or visual image is generated and recorded from a multiple gaseous discharge panel by projecting latent or visual image radiation from the gaseous discharges of the panel onto a photosensitive material adapted to receive, and record, or modulate the image. It is contemplated that such projected radiation may be visible or invisible relative to the human eye; that is, the image as projected, received, recorded, modulated and/or displayed may be any visible or invisible representation, likeness, copy, facsimile, etc., of the information represented by the gaseous discharge units.

As used herein, photosensitive surface is intended to include any plane or solid body of any suitable geometric shape, which plane or body is capable of receiving and recording the image radiation from the gaseous discharge. Also as used herein, recording is intended to include the storing, registering, duplicating, etc., of information in either visible or latent form corresponding to the projected image radiation. Such recording (or storing) can either be directly by the receiving surface or else modulated by such surface for recording or storing by a second surface member.

In the broad practice hereof, it is contemplated using a wide variety of materials and/or processes as the photosensitive surface,

In the specific practice hereof, there is used a system having the advantage of negative working, said system comprising image-wise charge deposition onto a dielectrio-coated, electrically conductive substrate, i.e., conductive paper, through a photoconductor sensitive to the radiation from the gaseous discharge panel. One such system is described in US. Pat. No. 3,502,408, which is hereby incorporated by reference.

If the photoconductor action spectrum is not sufficiently sensitive to the projected radiation emitted by the gaseous discharges of the panel, then it will be necessary to convert at least a portion of the radiation to an appropriate wavelength range wherein the photoconductor is more sensitive. This can be accomplished, for example, by means of a phosphor material incorporated somewhere between the gas discharge and the photoconductor. Preferably, the phosphor is positioned on or near the gas contacting surface of that panel dielectric nearer the photoconductor.

In gas discharge devices of the types contemplated herein, phosphors may be appropriately positioned within the device so as to be excited by radiation from the gas discharge of the device. For example, in a memory charge storage device of the Baker, et al. type, phosphors can be positioned on or be embedded in one or more charge storage dielectric surfaces as disclosed in US. Pat. No. 3,701,658, which is hereby incorporated by reference and copending US. Pat. application Ser. No. 98,846, filed Dec. 16, 1970, assigned to the same assignee as the present application and which is hereby incorporated by reference.

The presence of the phosphors within the device can also be utilized to provide color display as well as conversion of radiation to a wavelength range suitable for the photoconductor, the color being the result of radiation emitted by an excited phosphor alone or in combination with radiation emitted by the gas discharge.

This invention has several highly important advantages including photosensitive recording of an image from one side of a gaseous discharge panel while the image is being displayed and/or viewed from the other panel side without the use of mirrors.

Another most important advantage is that the image radiation emission can be different (if needed) for recording and for viewing, e.g., by the use of luminescent phosphors and various gaseous medium mixtures as previously discussed.

The charge pattern deposited on the dielectric coated, electrically conductive substrate may be made visible and fixed by means of liquid or powdered toners appropriately applied to the dielectric surface by means well known in the electrophotographic art, i.e., a powder toner-carrier mixture cascaded over the dielectric surface or by contacting the dielectric surface with an electrophoretic toner fluid.

DRAWINGS ILLUSTRATING GAS DISCHARGE DISPLAY/MEMORY PANEL AND INVENTION Reference is made to the accompanying drawings and the hereinafter discussed FIGS. 1 to 5 shown thereon illustrating a gas discharge display/memory panel of the Baker, et al. type.

FIG. 1 is a partially cut-away plan view of a gaseous discharge display/memory panel as connected to a diagrammatically illustrated source of operating potentials.

FIG. 2 is a cross-sectional view (enlarged, but not to proportional scale since the thickness of the gas volume, dielectric members and conductor arrays have been enlarged for purposes of illustration) taken on lines 2 2 of FIG. 1.

FIG. 3 is an explanatory partial cross-sectional view similar to FIG. 2 (enlarged, but not to proportional scale).

FIG. 4 is an isometric view of a gaseous discharge display/memory panel FIG. 5 is a diagrammatic view of the combination of the gaseous discharge display/memory panel and a photosensitive element of a recording device.

The panel comprises a pair of dielectric films l0 and 11 separated by a thin layer or volume of a gaseous discharge medium 12, the medium 12 producing a copious supply of charges (ions and electrons) which are alternately collectable on the surfaces of the dielectric members at opposed or facing elemental or discrete areas X and Y defined by the conductor matrix on nongas-contacting sides of the dielectric members, each dielectric member presenting large open surface areas, and a plurality of pairs of elemental X and Y areas. While the electrically operative structural members such as the dielectric members 10 and 11 and conductor matrixes l3 and 14 are all relatively thin 9being exaggerated in thickness in the drawings) they are formed on and supported by rigid nonconductive support members 16 and 17 respectively.

Preferably, one or both of the nonconductive support members 16 and 17 pass light produced by discharge in the elemental gas volumes. Preferably, they are transparent glass members. These members essentially define the overall thickness and strength of the panel. For example, the thickness of gas layer 12 as determined by spacer 15 is usually under 10 mils and preferstresses in the panel. Support members 16 and 17 also serve as heat sinks for heat generated by discharges and thus minimize the effect of temperature on operation of the device. If it is desired that only the memory function be utilized, then none of the members need be transparent to light.

The electrical properties of support members 16 and 17 are not critical so long as the electrodes are appropriately insulated from one another. The main function of support members 16 and 17 is to provide mechanical support and strength for the entire panel, particularly with respect to pressure differential acting on the panel. Ordinary one-fourth inch commercial grade soda lime plate glasses have been used for this purpose. Other glasses such as low expansion glasses or devitrified glass can be used provided they can withstand processing.

Spacer 15 may be made of the same glass material as dielectric films 10 and 11 and may be an integral rib formed on one of the dielectric members and fused to the other members to form a bakeable hermetic seal enclosing and confining the ionizable gas volume 12. However, a separate final hermetic seal may be effected by a high strength devitrified glass sealant S. Tubulation 18 is provided for exhausting the space between dielectric members 10 and 11 and filling that space with the volume of ionizable gas. For large panels small beadlike glass spacers such as shown at 15B may be located between conductor intersections and fused to dielectric members 10 and 11 to aid in withstanding stress on the panel and maintain uniformity of thickness of gas volume 12.

Conductor arrays 13 and 14 may be formed on support members 16 and 17 by a number of well-known processes, such as photoetching, vacuum deposition, stencil screening, etc. In the panel shown in FIG. 4, the center-to-center spacing of conductors in the respective arrays is about 17 mils for one typical commercial configuration. Transparent or semi-transparent conductive material such as tin oxide, gold, or aluminum can be used to form the conductor arrays and should have a resistance less than 3,000 ohms per line. Alternately, narrow opaque electrodes may be used so that discharge light passes the edges of the electrodes to reach the viewer. It is important to select a conductor material that is not attacked during processing by the dielectric material.

It will be appreciated that conductor arrays 13 and 14 may be wires or filaments of copper, gold, silver or aluminum or any other conductive metal or material. For example 1 mil wire filaments are commercially available and may be used in the invention. However, formed in situ conductor arrays are preferred since they may be more easily and uniformly placed on and adhered to the support plates 16 and 17.

Dielectric layer members 10 and l 1 are formed of an inorganic material and are preferably formed in situ as an adherent film or coating which is not chemically or physically affected during bake-out of the panel. One such material is a solder glass such as Kimble SG-68 58 manufactured by and icommerciall-y assignee of the present invention.

This glasslhas thermal expansion characteristics substantially matching the thermal expansion cliaracteris. tics of certain soda-lime glasses,and can be used as the dielectric layer when the support members 16 and 17 are soda-lime glass plates. Dielectric layers 10 and 11 should have a dielectric breakdown voltage of at least about 100 v. and be electrically homogeneous on a microscopic scale ,(e.g., no cracks, bubbles, dirt, surface films,.etc.). In addition, the surfaces of dielectric layers 10 and 1 1 should be good photoemitters of electrons in a baked out condition. Alternately, dielectric layers 10 and 11 may be overcoated with materials designed to produce good electron emission, .as in U.S. Pat. No. 3,634,719, issued to Roger E. Ernst hausen. Of course, for an optical display or viewing from one side of the panel and the projecting of an image from the other side of the panel, both of dielectric layers 10 and 11 should pass light generated on discharge and be transparent or translucent; preferably, both layers are optically transparent.

The preferred spacing between the facing surfaces of the two dielectric films is about 3 to 8 mils if the conductor arrays 13 and 14 have center-to-center spacing of about 17 mils.

The ends of conductors 14-1 14-4 and support members 17 extend beyond the enclosed gas volume 12 and are exposed'for the purpose of making electrical connection to interface and addressing circuitry 19. Likewise, the ends of conductors 13-1. 13-4 on support member 16 extend beyond the enclosed gas volthe display/memory panel, per se. In addition, by pro-.

viding a panel having greater uniformity in discharge characteristics throughout the panel, manufacturing tolerances of the interfacing circuitry can be made less rigid.

One mode of initiating operation of the panel will be described with reference to FIG. 3, which illustrates the condition of one elemental gas volume 30 having an elemental cross-sectional area and volume which is quite small relative to the entire volume and cross-sectional area of gas 12. The cross-sectional area of volume 30 is defined by the overlapping common elemental areas of the conductor arrays and the volume is equal to the product of the distance between the dielectric surfaces and the elemental area. It is apparent that if the conductor arrays are uniform and linear and are orthogonally (at right angles to each other) related each of elemental areas X and Y will be squares and if conductors of one conductor array are wider than conductors of the other conductor arrays, said areas will be rectangles. If the conductor arrays are at transverse angles relative to each other, other than the areas will be diamond shaped so that the cross-sectional shape of each volume is determined solely in the first instance by the shape of the common area of overlap between a l ailable from the conductors in the conductor arrays 13 and 14. The dotted lines30 are imaginary lines to show a boundary of one elemental volume about the center of which each elemental discharge takes place. It is known that the cross-sectional area of the discharge in a gas is affected by, inter alia, the pressure of the gas, such that, if desired, the discharge may even be constricted to'within an area smaller than the area of conductor overlap. By utilization of this phenomena, the light production may be confined or resolved substantially to the area of the elemental cross-sectional area defined by conductor overlap. Moreover, by operating at such pressure, charges (ions and electrons) produced on discharge are laterally confined so as to not materially affect operation of adjacent elemental discharge volumes.

In the instance shown in FIG. 3, a conditioning discharge about the center of elemental volume 30 has been initiated by application to conductor 13-1 and conductor 14-1 firing potential V, as derived from a source 35 of variable phase, for example, and source 36 of sustaining potential V, (which may be a sine wave, for example). The potential V, is added to the sustaining potential V, as sustaining potential V, increases in magnitude to initiate the conditioning discharge about the center of elemental volume 30 shown in FIG. 3. There, the phase of the source 35 of potential V, has been adjusted into adding relation to the alternating voltage from the source 36 of sustaining voltage V, to provide a voltage V,, whenswitch 33 has been closed, to conductors 13-1 and 14-1 defining elementary gas volume 30 sufficient (in time and/or magnitude) to produce a light generating discharge centered about discrete elemental gas volume 30. At the instant shown, since conductor 13-1 is positive, electrons 32 have collected on and are moving to an elemental area of dielectric member 10 substantially corresponding to the area of elemental gas volume 30 and the less mobile positive ions 31 are beginning to collect on the opposed elemental area of dielectric member 11 since it is negative. As these charges build up, they constitute a back voltage opposed to the voltage applied to conductors 13-1 and 14-1 and serve to terminate the discharge in elemental gas volume 30 for the remainder of a half cycle.

During the discharge about the center of elemental gas volume 30, photons are produced which are free to move or pass through gas medium 12, as indicated by arrows 37, to strike or impact remote surface areas of photoemissive dielectric members 10 and 11, causing such remote areas to release electrons 38. Electrons 38 are created in every other discrete elemental gas volume, and condition these volumes for operation at a firing potential V, which is lower in magnitude than the firing potential V for the initial discharge.

Thus, elimination of physical obstructions or barriers between discrete elemental volumes permits photons to travel via the space occupied by the gas medium 12 to remote surface areas of dielectric members 10 and 11 and provides a mechanism for supplying free electrons to all elemental gas volumes, thereby conditioning all discrete elemental gas volumes for subsequent discharges, respectively, at a substantially uniform lower applied potential. While in FIG. 3 a single elemental volume 30 is shown, it will be appreciated that an entire row (or column) of elemental gas volumes may be maintained in a fired condition during normal operation of the device with the light produced thereby being masked or blocked off from the normal viewing area and not used for display purposes. It can be expected that in some applications there will always be at least one elemental volume in a fired condition and producing light in a panel, and in such applications it is not necessary to provide separate discharge or generation tential for initiating an initial discharge. Thus, by irradiating the panel with ultraviolet radiation or by including a radioactive material within the glass materials or gas space, all discharge volumes can be operated at uniform potentials from addressing and interface circuit 19.

Since each discharge is terminated upon a build-up or storage of charges at opposed pairs of elemental areas, the light produced is likewise terminated. In fact, light production lasts for only a small fraction of a half cycle of applied alternating potential and, depending on design parameters, is typically in the submicrosecond range.

After the initial firing or discharge of discrete elemental gas volume 30 by a firing potential V,, switch 33 may be opened so that only the sustaining voltage V, from source 36 is applied to conductors 13-1 and 14-1. Due to the storage of charges at the opposed elemental areas X and Y, the elemental gas volume 30 will discharge again at or near the peak of the following half cycle of V, (which is of opposite polarity) to again produce a momentary pulse of light. At this time, due to reversal of field direction, electrons 32 will collect on and be stored on elemental surface area Y of dielectric member 11 and positive ions 31 will collect and be stored on elemental surface area X of dielectric member 10. After a few cycles of sustaining voltage V,,, the times of discharges become symmetrically located with respect to the wave form of sustaining voltage V At remote elemental volumes, as for example, the elemental volumes defined by conductors 14-1 with conductors 13-2 and 13-3, a uniform magnitude or potential V from source is selectively added by one or both of switches 34-2 or 34-3 to the sustaining voltage V,, shown as 36', to fire one or both of these elemental discharge volumes. Due to the presence of free electrons produced by photons from the. discharge centered about elemental volume 30, each of these remote dis-.

crete elemental volumes have been conditioned for operation at uniform firing potential V In order to turn off an elemental gas volume (i.e., terminate a sequence of discharges representing the on state), the sustaining voltage may be removed.

However, since this would also turn off other ele-' but may be curved, curvature of facing surfaces of each plate being complementary to each other, so that the gap between plates remains substantially uniform over their entire surfaces. While the preferred conductor arrangement is of the crossed grid type as shown herein, it is likewise apparent that where an infinite variety of two dimensional display patterns are not necessary, as where specific standardized visual shapes (e.g., numerals, letters, words, etc.) are to be formed and image resolution is not critical, theconductors may be shaped accordingly. Reference is made to British Pat. Specification No. 1,302,148 and US. Pat. No. 3,711,733 wherein non-grid electrode arrangement are illustrated.

The device shown in FIG. 4 is a panel having a large number of elemental volumes similar to elemental volume 30 (FIG. 3). In this case more room is provided to make electrical connection to the conductor arrays 13 and 14, respectively, by extending the surfaces of support members 16 and 17' beyond seal 15S, alternate conductors being extended on alternatesides. Support members 16' and 17 are transparent. The dielectric coatings are not shown in FIG. 4 but are likewise transparent so that the panel may be viewed from either side.

In FIG. 5 there is illustrated the combination of a discharge panel 100, an optical system 101, and a recording system 102. In the opposite direction from panel 100 can be a human eye (not illustrated). As already noted hereinbefore, the recording system 102 comprises a photoconductor material, a dielectric-coated, electrically conductive paper, and means for applying an electric field across the photoconductor and paper.

I claim:

1. In the operation of an apparatus comprising in combination a gaseous discharge display/memory panel and an image recording device, said panel being characterized by an ionizable gaseous medium in a gas chamber formed by a pair of dielectric material members having opposed charge storage surfaces, which dielectric material members are capable of transmitting light therethrough and are respectively backed by a series of parallel-like electrode members, the electrode members behind each dielectric material member being transversely oriented with respect to the electrode members behind the opposing dielectric material member so as to define a plurality of discrete discharge volumes, each of which constitutes a discharge unit, and wherein the gas is selectively ionized within each discharge unit by operating voltages applied to the transversely oriented electrode members, said image recording device being characterized by a photosensitive surface facing one of said dielectric material members for directly receiving and recording an image, the improvement which comprises generating an image comprised of one or more gaseous discharge units such that image radiation is emitted from the discharge units in opposite directions through both said dielectric material members, said image emerging through said one dielectric material member being received by one side of a photoconductive material thereby causing a charge pattern corresponding to the image to be deposited onto a dielectric-coated, electrically conductive paper positioned on the opposite side of the photoconductor, when an electric field is applied across the array of photoconductor and paper.

2. The invention of claim I wherein toner is applied to the dielectric coating so as to make the deposited charge pattern visible.

3. The invention of claim 1 wherein a phosphor is positioned between the gas discharges and the photoconductive material.

4. The invention of claim 3 wherein the phosphor is selected so as to convert the gas discharge radiation to a wave length range corresponding to the action spectrum of the photoconductor material.

5. An image display and recording apparatus adapted to simulataneously display and record an image comprising in combination a gaseous discharge display/- memory panel and an image recording device, said panel comprising a pair of spaced-apart nonconductive support members, a pair of conductor arrays arranged one on each of the confronting surfaces of said support members, the arrays being in transverse relative orientation so as to provide a series of crosspoints therebetween, each defining a discharge unit, a thin dielectric material coating on the confronting surfaces of each of the support members and conductor arrays defining therebetween a sealed gas chamber, an ionizable gaseous medium contained in said chamber, said dielectric material coating being adapted to insulate said conductor arrays from said ionizable gaseous medium contained in said chamber and for storing charges emitted by said gaseous discharge and both said support members and dielectric material coatings being capable of transmitting light therethrough, and means for selectively applying operating voltages to said transversely oriented electrode members for selectively ionizing said discharge units for generating an image which is radiated in opposite directions through both said dielectric material coatings and support members; and said image recording device including a photosensitive surface facing one of said support members for directly receiving and recording the image radiated from said discharge units through said one support member whereby said image may be simultaneously directly observed through the other of said support members and received by one side of a photoconductive material thereby causing a charge pattern corresponding to the image to be deposited onto a dielectriccoated, electrically conductive paper positioned on the opposite side of the photoconductor, when an electric field is applied across the array of photoconductor and paper. 1

6. The invention of claim 5 wherein toner is applied to the dielectric coating so as to make the deposited charge pattern visible.

7. The invention of claim 5 wherein a phosphor is positioned between the gas discharges and the photoconductive material.

8. The invention of claim 7 wherein the phosphor is selected so as to convert the gas discharge radiation to a wave length range corresponding to the action spectrum of the photoconductor material.

9 An image display and recording apparatus adapted to simultaneously display and record an image comprising in combination a gaseous discharge display/memory panel and an image recording device, said panel comprising an ionizable gaseous medium in a gas chamber formed by a pair of dielectric material members having opposed charge storage surfaces, which dielectric material members are capable of transmitting light therethrough and are respectively backed by a'series of parallel-like electrode members, the electrode members behind each dielectric material member being transversely oriented with respect to the electrode members behind the opposing dielectric material member so as to define a plurality of discrete discharge volumes, each of which constitutes a discharge unit, and

means for selectively applying operating voltages to pattern corresponding to the image to be deposited onto a dielectric-coated, electrically conductive paper positioned on the opposite side of the photoconductor, when an electric field is applied across the array of photoconductor and paper.

10. The invention of claim 9 wherein toner is applied to the dielectric coating so as to make the deposited charge pattern visible.

11. The invention of claim 9 wherein a phosphor is positioned between the gas discharges and the photoconductive material.

12. The invention of claim 11 wherein the phosphor is selected so as to convert the gas discharge radiation to a wave length range corresponding to the action spectrum of the photoconductor material. 

1. In the operation of an apparatus comprising in combination a gaseous discharge display/memory panel and an image recording device, said panel being characterized by an ionizable gaseous medium in a gas chamber formed by a pair of dielectric material members having opposed charge storage surfaces, which dielectric material members are capable of transmitting light therethrough and are respectively backed by a series of parallel-like electrode members, the electrode members behind each dielectric material member being transversely oriented with respect to the electrode members behind the opposing dielectric material member so as to define a plurality of discrete discharge volumes, each of which constitutes a discharge unit, and wherein the gas is selectively ionized within each discharge unit by operating voltages applied to the transversely oriented electrode members, said image recording device being characterized by a photosensitive surface facing one of said dielectric material members for directly receiving and recording an image, the improvement which comprises generating an image comprised of one or more gaseous discharge units such that image radiation is emitted from the discharge units in opposite directions through both said dielectric material members, said image emerging through said one dielectric material member being received by one side of a photoconductive material thereby causing a charge pattern corresponding to the image to be deposited onto a dielectric-coated, electrically conductive paper positioned on the opposite side of the photoconductor, when an electric field is applied across the array of photoconductor and paper.
 2. The invention of claim 1 wherein toner is applied to the dielectric coating so as to make the deposited charge pattern visible.
 3. The invention of claim 1 wherein a phosphor is positioned between the gas discharges and the photoconductive material.
 4. The invention of claim 3 wherein the phosphor is selected so as to convert the gas discharge radiation to a wave length range corresponding to the action spectrum of the photoconductor material.
 5. An image display and recording apparatus adapted to simulataneously display and record an image comprising in combination a gaseous discharge display/memory panel and an image recording device, said panel comprising a pair of spaced-apart non-conductive support members, a pair of conductor arrays arranged one on each of the confronting surfaces of said support members, the arrays being in transverse relative orientation so as to provide a series of cross-points therebetween, each defining a discharge unit, a thin dielectric material coating on the confronting surfaces of each of the support members and conductor arrays defining therebetween a sealed gas chamber, an ionizable gaseous medium contained in said chamber, said dielectric material coating being adapted to insulate said conductor arrays from said ionizable gaseous medium contained in said chamber and for storing charges emitted by said gaseous discharge and both said support members and dielectric material coatings being capable of transmitting light therethrough, and means for selectively applying operating voltages to said transversely oriented electrode members for selectively ionizing said discharge units for generating an image which is radiated in opposite directions through both said dielectric material coatings and support members; and said image recording device including a photosensitive surface facing one of said support members for directly receiving and recording the image radiated from said discharge units through said one support member whereby said image may be simultaneously directly observed through the other of said support members and received by one side of a photoconductive material thereby causing a charge pattern corresponding to the image to be deposited onto a dielectriccoated, electrically conductive paper positioned on the opposite side of the photoconductor, when an electric field is applied across the array of photoconductor and paper.
 6. The invention of claim 5 wherein toner is applied to the dielectric coating so as to make the deposited charge pattern visible.
 7. The invention of claim 5 wherein a phosphor is positioned between the gas discharges and the photoconductive material.
 8. The invention of claim 7 wherein the phosphor is selected so as to convert the gas discharge radiation to a wave length range corresponding to the action spectrum of the photoconductor material.
 9. An image display and recording apparatus adapted to simultaneously display and record an image comprising in combination a gaseous discharge display/memory panel and an image recording device, said panel comprising an ionizable gaseous medium in a gas chamber formed by a pair of dielectric material members having opposed charge storage surfaces, which dielectric material members are capable of transmitting light therethrough and are respectively backed by a series of parallel-like electrode members, the electrode members behind each dielectric material member being transversely oriented with respect to the electrode members behind the opposing dielectric material member so as to define a plurality of discrete discharge volumes, each of which constitutes a discharge unit, and means for selectively applying operating voltages to said transversely oriented electrode members for selectively ionizing said discharge units for generating an image which is radiated in opposite directions through both said dielectric material members, and said image recording device including a photosensitive surface facing one of said dielectric material members for directly receiving and recording the image radiated from said discharge units through said one dielectric material member, whereby said image may be simultaneously observed directly through the other of said Dielectric material members and received by one side of a photoconductive material thereby causing a charge pattern corresponding to the image to be deposited onto a dielectric-coated, electrically conductive paper positioned on the opposite side of the photoconductor, when an electric field is applied across the array of photoconductor and paper.
 10. The invention of claim 9 wherein toner is applied to the dielectric coating so as to make the deposited charge pattern visible.
 11. The invention of claim 9 wherein a phosphor is positioned between the gas discharges and the photoconductive material.
 12. The invention of claim 11 wherein the phosphor is selected so as to convert the gas discharge radiation to a wave length range corresponding to the action spectrum of the photoconductor material. 